FIELD OF THE INVENTION
This invention relates, in general, to gas masks and, in particular to a new and useful gas mask having a supply connection for a breathing gas which effects the automatic shut-off of the breathing gas connection when it is disconnected from the mask.
The invention relates particularly to a closed cycle gas mask and breathing equipment for supplying breathing air operation under pressure which includes an inhalation line and an exhalation line which open into a joint or tubular connection of a mask, wherein during the release of the connection the escaping of respiratory air from the breathing equipment is prevented by means of a switch-off device.
A similar closed cycle gas mask and breathing equipment is known from German patent No. 34 29 345.
In the known closed-cycle breathing equipment the pressure in the respiratory cycle is generated and controlled by means of a pneumatic piston-cylinder unit fed by a respiratory air source by exerting a respective pressure on an air bag in the respiratory cycle. If a sudden pressure drop occurs, e.g. due to the separation of the mask from the face or from the apparatus, the air bag is compressed by means of the piston-cylinder aggregate, and the circulation of the respiratory air breaks down due to the missing pressure. The known switch-off device has the disadvantage that it has to be actuated by means of complex pneumatic control elements and monitors.